Medium size- Best for puppies, teacups, toy breeds weighing 1-4 kilos. Large Size- Best for small to medium breeds weighing 4-6 kilos. XL- Best for breeds weighing 6-8 kilos. XXL- Best for breeds weighing 8-12 kilos 3XL- Also available *The above weighing is depending to the dog/ pet’s weight, size and built.